Prey Spectrum Research Articles

Prey availability and diet composition of the Grey plover (Pluvialis squatarola) during migration on the South-Western Black Sea coast, Bulgaria

Migratory waders use stopover sites to refuel for the next stages of their migration, relying on seasonally abundant prey. Migration success depends on food quality and availability at these key sites. We studied the diet composition and preferences of the Grey Plover (Pluvialis squatarola) at its migration stopover at Pomorie Lake on the South-Western Black Sea coast, Bulgaria through DNA metabarcoding of faeces collected in autumn 2020 and spring 2021. Prey availability samples were also collected from the surf zone and the supralittoral sandy shore habitats in the study area.Grey Plover had a broad diet spectrum, with 332 prey taxa in total identified by metabarcoding. Both terrestrial and marine taxa were found, suggesting that the birds use multiple coastal habitats for foraging. Terrestrial arthropods, particularly insects, predominated in the Grey Plover diet; mytilid bivalves were the most represented marine taxon. The birds had a generalist feeding strategy, with diverse prey items eaten in small quantities. Most Grey Plovers fed on insects (Diptera, Lepidoptera, Hymenoptera), but some individuals showed specialisation for other taxa (mussels, spiders, polychaetes). The most abundant potential prey in the environment were not the most frequently consumed, but it is possible the prey sampling failed to capture the whole spectrum of available prey due to methodological limitations.We found no significant seasonal variation in Grey Plover diet composition, but the proportions of some prey taxa in the diet changed slightly, probably reflecting seasonal differences in their abundance and activity in coastal habitats.Our results contribute to the knowledge of Grey Plover diet, prey choice and habitat use in a little-studied region, and could help design effective conservation measures to preserve habitat quality at stopover sites for this wader and others with similar ecology.

To pool or not to pool: Pooled metabarcoding does not affect estimates of prey diversity in spider gut content analysis

Abstract Gut content metabarcoding has provided important insights into the food web ecology of spiders, the most dominant terrestrial arthropod predators. In small invertebrates, like spiders, gut content analysis is often performed on whole body DNA extracts of individual predators, from which prey sequences are selectively enriched and sequenced. Since many spider species are generalist predators, large numbers of samples comprising individual spider specimens must be analysed to recover an exhaustive image of a spider species' prey spectrum, which is costly and time‐consuming. Pooled processing of bulk samples of multiple specimens has been suggested to reduce the necessary workload and cost while still recovering a representative estimate of the prey diversity. However, it is still unclear if pooling approaches lead to bias in recovering the prey spectrum and if the results are comparable with data from individually processed spiders. Here, we test the effects of metabarcoding pooled spider gut content on the recovered taxonomic diversity and composition of prey. Using a newly adapted primer pair, which efficiently enriches COI barcode sequences of diverse arthropod prey groups while suppressing spider amplification, we test if pooling leads to reduced taxonomic diversity or skewed estimates of prey composition. Our results show that pooling and individual processing recover highly correlated taxonomic diversity and composition of prey. The only exception are very rare prey items which were less well recovered by pooling. Our results support pooling as a cost‐effective and time‐efficient approach to recover the diet of generalist predators for population‐level studies of spider trophic interactions.

Switch or perish? Prey–predator interactions in a Mediterranean area

AbstractPredator–prey relationships can influence community processes, and a rich prey spectrum is important to favour carnivore conservation, as well as to buffer single prey towards intensive predation. Antipredator behavioural responses can occur and can be dynamic in time and space, which may generate counter‐responses in predators. However, data are scarce on their role in modulating carnivore diet and behaviour. Data are especially needed for European landscapes that are largely anthropized and have been recently recolonized by large carnivores. In a protected area in central Italy recently recolonized by the wolf and hosting a rich community of wild ungulates, we studied the interactions between this predator and three ungulate species. At the initial stage of wolf recovery, the fallow deer and the wild boar were the main prey, while the roe deer was a minor food item. Through camera‐trapping and predator food habits, we assessed temporal changes in wolf–prey relationships throughout 5 years (2017–2022). Wolf detection rates were spatially associated with those of fallow deer and wild boar, but shrub cover was positively related to predator and negatively to prey, suggesting possible prey avoidance of sites with lower visibility and greater predation risk. Throughout the years, the fallow deer increased its diurnal activity, with a decreasing temporal overlap with the predator. The wolf showed crepuscular/nocturnal activity, with an increased synchronization with the wild boar, which replaced the fallow deer as first prey. No support for major spatiotemporal responses was reported for wild boar and roe deer. With the ongoing recovery of carnivores across Europe, conservation priorities may emphasize the need to maintain an efficient ecological role of predators. Our results support the role of antipredator responses in modulating predator behaviour and diet and emphasize the importance of a diverse spectrum of wild prey to ensure the conservation of the ecological role of carnivores.

Resource supply and intraspecific variation in inducible defense determine predator–prey interactions in an intraguild predation food web

This study investigated the dynamics of reciprocal phenotypic plasticity entailing inducible defense and offense in freshwater ciliate communities in response to altered resource supply and the extent of intraspecific trait variation. Communities consisted of Euplotes octocarinatus (intraguild prey) capable of inducible defense to escape predation, Stylonychia mytilus (intraguild predator) capable of inducible offense to expand its prey spectrum, and Cryptomonas sp. (algal resource). The extent of inducible defense was tested in ten different Euplotes strains in response to freeze-killed Stylonychia concentrate, revealing significant differences in their width and length development. In a subsequent 30-day experiment, four strains were incubated in monoculture and mixture with Stylonychia under continuous and pulsed microalgae supply. The polyclonal Euplotes population outperformed the monoclonal populations, except one, which developed the most pronounced inducible defense and retained the highest biovolume. Stylonychia fluctuated in size, but dominated all communities irrespective of clonal composition. Pulsed resource supply promoted biovolume production of both species. However, periods of resource depletion resulted in more Stylonychia resting cysts, allowing Euplotes to resume growth. Our study provides new insights into interactions of induced defense and intraguild predation under variable environmental conditions, emphasizing the relevance of intraspecific trait variation for predator–prey interactions and community dynamics.

Diet in phenotypically divergent sympatric species of African weakly electric fish (genus: Campylomormyrus)-A hybrid capture/HTS metabarcoding approach.

Ecological speciation within the mormyrid genus Campylomormyrus resulted in sympatric species exhibiting divergence in their feeding apparatus and electric organ discharge (EOD). This study documents the overall diet of the genus Campylomormyrus and examines the hypothesis that the Campylomormyrus radiation is caused by adaptation to different food sources. We performed diet assessment of five sympatric Campylomormyrus species (C. alces, C. compressirostris, C. curvirostris, C. tshokwe, C. numenius) and their sister taxon Gnathonemus petersii with markedly different snout morphologies and EODs using hybrid capture/HTS DNA metabarcoding of their stomach contents. Our approach allowed for high taxonomic resolution of prey items, including benthic invertebrates, allochthonous invertebrates and vegetation. Comparisons of the diet compositions using quantitative measures and diet overlap indices revealed that all species are able to exploit multiple food niches in their habitats, that is fauna at the bottom, the water surface and the water column. A major part of the diet is larvae of aquatic insects, such as dipterans, coleopterans and trichopterans, known to occur in holes and interstitial spaces of the substrate. The results indicate that different snout morphologies and the associated divergence in the EOD could translate into different prey spectra. This suggests that the diversification in EOD and/or morphology of the feeding apparatus could be under functional adaptation.

Effect of predatory bacterial mixtures on biolysis of waste activated sludge to improve dewatering performance

ABSTRACTThe generation of surplus sludge during biological wastewater treatment has become a prevalent issue, necessitating the development of a dewatering approach that is efficient, economically feasible, and ecologically sound. Bdellovibrio-and-like-organisms (BALOs) are obligatory parasitic bacteria that prey on an array of bacteria. In this study, different BALO strains were isolated and purified from waste activited sludge (WAS). Anti-predation host strains were applied to screen the BALO strains with different host-range to minimize the overlap of the biolysis prey spectrum. In addition, the BALO strains with different host preferences were mixed for sludge biolysis treatment efficiency comparison. The results indicated that the capillary suction time and the bound water content in the WAS treated with the mixed BALOs were significantly decreased by 25.9% ± 1.7% and 5.2% ± 1.2%, respectively, compared to those treated with the single BALO strain. The soluble chemical oxygen demand concentration in the mixed BALOs treated group was increased by 31.2% ± 0.7% than that treated with the single strain. The findings indicate that the mixed strains used in the treatment process resulted in a notable enhancement of both sludge dewatering performance and lysis degree. In addition, the abundance of Proteobacteria treated with the BALO mixtures decreased by 69.1% than the single strain treated one which demonstrated that the BALO mixture expanded the sludge host lysis spectrum. This study revealed the different effects of single and mixed strains on sludge community structure, suggesting that the BALO host-range expansion is crucial to further improve sludge dewatering performances.

A comparison of live versus kill pitfall traps to assess the diet of carabids through a metabarcoding approach

AbstractMetabarcoding approaches are powerful tools to unravel trophic relationships between predators and prey. To apply metabarcoding analyses on invertebrate gut contents, specimens must be well preserved from DNA degradation, thus the trapping method should be selected accordingly. Dry pitfall traps are commonly assumed to provide a better DNA preservation than traps that use a killing agent. However, this assumption has never been specifically tested for gut content analyses. In our study, we compared how two types of pitfall trapping, dry vs. with brine, affect the conservation of prey DNA contained in the digestive tract of predators and subsequent metabarcoding analyses. We placed dry and ‘classic’ pitfall traps in oilseed rape fields within an intensive agricultural area in the French Nouvelle‐Aquitaine region. Traps were set up in autumn and compared for carabid trapping efficiency as well as our capacity to retrieve dietary information from the digestive tract of the main carabid species, Nebria salina (Fairmaire & Laboulbène) and Calathus fuscipes (Goeze) (both Coleoptera: Carabidae). The PCR success rate was higher in dry pitfall traps compared to classic ones for N. salina. We hypothesise that this was due to the presence of PCR inhibitors in the gut of this species. The ability to sequence prey DNA did not differ between specimens caught in both trap types. The list of preyed species was similar between both trap types. However, sequencing yielded more prey operational taxonomic units (OTUs) from specimens caught in dry pitfall traps, leading to differences in prey community composition and a greater ability to reconstruct prey community. Our analyses also shed light on the prey spectrum of C. fuscipes and N. salina in oilseed rape in autumn.

Testing the effectiveness of different wash protocols to remove body surface contaminants in invertebrate food web studies.

Molecular gut content analysis via diagnostic PCR or high-throughput sequencing (metabarcoding) of consumers allows unravelling of feeding interactions in a wide range of animals. This is of particular advantage for analyzing the diet of small invertebrates living in opaque habitats such as the soil. Due to their small body size, which complicates dissection, microarthropods are subjected to whole-body DNA extraction-step before their gut content is screened for DNA of their food. This poses the problem that body surface contaminants, such as fungal spores may be incorrectly identified as ingested food particles for fungivorous species. We investigated the effectiveness of ten methods for body surface decontamination in litter-dwelling oribatid mites using Steganacarus magnus as model species. Furthermore, we tested for potential adverse effects of the decontamination techniques on the molecular detection of ingested prey organisms. Prior to decontamination, oribatid mites were fed with an oversupply of nematodes (Plectus sp.) and postmortem contaminated with fungal spores (Chaetomium globosum). We used diagnostic PCR with primers specific for C. globosum and Plectus sp. to detect contaminants and prey, respectively. The results suggest that chlorine bleach (sodium hypochloride, NaClO, 5%) is most efficient in removing fungal surface contamination without significantly affecting the detection of prey DNA in the gut. Based on these results, we provide a standard protocol for efficient body surface decontamination allowing to trace the prey spectrum of microarthropods using molecular gut content analysis.

Morphology of the male reproductive system and sperm ultrastructure of the green lacewing, Chrysopa pallens (Rambur, 1838) (Neuroptera: Chrysopidae)

BackgroundChrysopa pallens is one of the most beneficial and effective natural predators, and is famous for its extensive distribution, wide prey spectrum, and excellent reproductive performance. This study examined the anatomy and fine structure of the C. pallens reproductive system and spermatogenesis.ResultsThe male reproductive system of C. pallens comprises a pair of testes, a vas deferens, seminal vesicles, accessory glands, and short ejaculatory ducts. The testes were already mature on the day of emergence, but the accessory glands did not mature until 5 days post-emergence. In early spermatids, the flagellum had an axoneme on one side of the two mitochondrial derivatives. The nucleus was surrounded by parallel crystalline and paracrystalline materials. The spermatid envelope extends towards the paracrystalline material in a tail-shaped wing. In mature spermatids, the axoneme is located between the two accessory bodies and mitochondrial derivative sets. The parallel-crystalline and paracrystalline materials disappeared. In the testes, the wall of seminal cysts consists of a layer of epithelium, a muscular-connective sheath, and several vesicles of different sizes. The mature seminal cysts contained 128 spermatozoa. The accessory gland is composed of six parts: ventral papilla-like protuberance, anterior glandular lobe, lateral glandular lobe, seminal cyst, posterior kidney-shaped lobe, and posterior papilla-like protuberance. Muscle fibers and secretory granules are extensive.ConclusionsThis study provides information on the reproductive system of C. pallens and offers a resource for taxonomy and reproductive biology.

Five phototrophic <italic>Scrippsiella</italic> species lacking mixotrophic ability and the extended prey spectrum of <italic>Scrippsiella acuminata</italic> (Thoracosphaerales, Dinophyceae)

Mixotrophic dinoflagellates act as primary producers, prey, and predators in marine planktonic food webs, whereas exclusively autotrophic dinoflagellates are primary producers and prey. Species of the dinoflagellate genus <i>Scrippsiella</i> are commonly found in marine ecosystems and sometimes cause harmful red tides. Among the 28 formally described <i>Scrippsiella</i> species, <i>S. acuminata</i> has been found to be mixotrophic and two unidentified species have been found to be mixotrophic. To determine whether the other species in this genus are similarly mixotrophic, the mixotrophic ability of <i>S. donghaiensis</i> SDGJ1703, <i>S. lachrymosa</i> SLBS1703, <i>S. masanensis</i> SSMS0908, <i>S. plana</i> SSSH1009A, and <i>S. ramonii</i> VGO1053 was explored using 15 potential prey items, including 2-µm fluorescently labeled microspheres (FLM) and heterotrophic bacteria (FLB), the cyanobacterium <i>Synechococcus</i> sp., and various microalgal prey species. The ability of <i>S. acuminata</i> to feed on FLM and FLB was also investigated. We found that <i>S. donghaiensis</i>, <i>S. lachrymosa</i>, <i>S. masanensis</i>, <i>S. plana</i>, and <i>S. ramonii</i> did not feed on any potential prey tested in this study, indicating a lack of mixotrophy. However, <i>S. acuminata</i> fed on both FLM and FLB, confirming its mixotrophic ability. These results lowered the proportion of mixotrophic species relative to the total number of tested <i>Scrippsiella</i> species for mixotrophy from 100% to 29–38%. Owing to its mixotrophic ability, <i>S. acuminata</i> occupies an ecological niche that is distinct from that of <i>S. donghaiensis</i>, <i>S. lachrymosa</i>, <i>S. masanensis</i>, <i>S. plana</i>, and <i>S. ramonii</i>.

Contemporary issues, current best practice and ways forward in soil protist ecology.

Soil protists are increasingly studied due to a release from previous methodological constraints and the acknowledgement of their immense diversity and functional importance in ecosystems. However, these studies often lack sufficient depth in knowledge, which is visible in the form of falsely used terms and false- or over-interpreted data with conclusions that cannot be drawn from the data obtained. As we welcome that also non-experts include protists in their still mostly bacterial and/or fungal-focused studies, our aim here is to help avoid some common errors. We provide suggestions for current terms to use when working on soil protists, like protist instead of protozoa, predator instead of grazer, microorganisms rather than microflora and other terms to be used to describe the prey spectrum of protists. We then highlight some dos and don'ts in soil protist ecology including challenges related to interpreting 18S rRNA gene amplicon sequencing data. We caution against the use of standard bioinformatic settings optimized for bacteria and the uncritical reliance on incomplete and partly erroneous reference databases. We also show why causal inferences cannot be drawn from sequence-based correlation analyses or any sampling/monitoring, study in the field without thorough experimental confirmation and sound understanding of the biology of taxa. Together, we envision this work to help non-experts to more easily include protists in their soil ecology analyses and obtain more reliable interpretations from their protist data and other biodiversity data that, in the end, will contribute to a better understanding of soil ecology.

Adding complexity to soil food webs: Myxobacteria have broad predation spectra with bacteria, yeasts and filamentous fungi in vitro

In the multifaceted soil habitat, predation is one of the most successful strategies for obtaining food. An example of prokaryotic predators is myxobacteria. Although the prey spectra of some myxobacteria have been the subject of numerous studies, these myxobacteria are usually rare in soils compared to other myxobacterial families. Consequently, predation assays featuring easily cultivable myxobacteria provide only limited information on the myxobacterial potential and their interactions with organisms in the soil. Therefore, the prey spectrum of representatives of more common families was tested and compared with members of the model family Myxococcaceae. In a newly developed assay, the extent of lysis was tested against various Gram-positive and Gram-negative bacteria, as well as four yeasts. It was shown that Kofleria flava and Haliangium ochraceum have an equally diverse prey spectrum as the model genera Myxococcus and Corallococcus. However, less well-studied myxobacteria often lyse the prey colonies to a larger extent. Yeasts were lysed just as efficiently as bacteria. Furthermore, it was tested whether different myxobacteria can inhibit the growth of filamentous fungi. Almost every strain was able to prevent the spread of at least one fungus. H. ochraceum showed the highest activity and inhibited all fungi, including plant pathogenic Fusarium. These multiple interactions together with the high relative abundance in situ, suggest that myxobacteria, especially understudied families, could have a more important role in the soil food web than previously thought. The individual interaction spectra of the different myxobacteria provide only a glimpse at the complex relationships between the organisms in soil, which still remain understudied.

Carnivores from Draby 3 (central Poland): The latest record of Lycaon lycaonoides (Kretzoi, 1938) and the final accord in the long history of ancient faunas

The occurrence of the phylogenetic lineage of the genus Lycaon covers the entire Pleistocene. A younger form, Lycaon lycaonoides, was recorded from 68 African, Eurasian and North American localities, ranged between 1.8 and 0.4 myr. Among them, six localities are in the territory of Poland, with especially important the youngest record from Draby 3, dated at MIS 11. It seems to be the latest occurrence of this species elsewhere. Draby 3 documented the last, relict occurrence of Lycaon lycaonoides after the most extreme glaciation of MIS 12, which was crucial for a significant decrease in numbers and density, or the complete disappearance of many ancient carnivores. Lycaon lycaonoides was ecologically flexible species able to hunt in a wide prey spectrum; its size, comparable with that of the largest extant Canis lupus, high intelligence, social lifestyle and pack hunting guaranteed the leading position among other ancient large carnivores. This species was a member of a stable by 1.5 myr carnivore paleoguild, one of the top carnivores and the dominant canid. It was also well adapted to changing environmental conditions initiated by glacial-interglacial cycles. It seems that climatic changes have not affected Lycaon lycaonoides as much as previously considered. The main factor responsible for the lycaon decline, alongside with climatic changes, would be the arrival of newcomers of African origin like Panthera spelaea fossilis and Crocuta crocuta spelaea. Lycaon lycaonoides was able to survive longer than other ancient carnivores. It disappeared first in southern Europe (Iberian and Italian Peninsulas), in areas where lion and hyena appeared for the first time. Gradually as the density and abundance of both social and highly intelligent species increased, a compact and wide geographic range of this species started to shrink up to isolated areas located far away one from another. The final collapse of the lycaon population and its disappearance took place during MIS 12. The balance between canids has been broken and a critical point in the lycaon-wolf relationship was passed at that time. During MIS 11, the lycaon was already too rare to be a real competitor and a limiting factor for the wolf. It was also the time when the lycaon completely disappeared. As soon as the lycaon disappeared in Eurasia, a slowly increase in the size of the wolf has been observed.

Lack of mixotrophy in three Karenia species and the prey spectrum of Karenia mikimotoi (Gymnodiniales, Dinophyceae)

Exploring mixotrophy of dinoflagellate species is critical to understanding red-tide dynamics and dinoflagellate evolution. Some species in the dinoflagellate genus Karenia have caused harmful algal blooms. Among 10 Karenia species, the mixotrophic ability of only two species, Karenia mikimotoi and Karenia brevis, has been investigated. These species have been revealed to be mixotrophic; however, the mixotrophy of the other species should be explored. Moreover, although K. mikimotoi was previously known to be mixotrophic, only a few potential prey species have been tested. We explored the mixotrophic ability of Karenia bicuneiformis, Karenia papilionacea, and Karenia selliformis and the prey spectrum of K. mikimotoi by incubating them with 16 potential prey species, including a cyanobacterium, diatom, prymnesiophyte, prasinophyte, raphidophyte, cryptophytes, and dinoflagellates. Cells of K. bicuneiformis, K. papilionacea, and K. selliformis did not feed on any tested potential prey species, indicating a lack of mixotrophy. The present study newly discovered that K. mikimotoi was able to feed on the common cryptophyte Teleaulax amphioxeia. The phylogenetic tree based on the large subunit ribosomal DNA showed that the mixotrophic species K. mikimotoi and K. brevis belonged to the same clade, but K. bicuneiformis, K. papilionacea, and K. selliformis were divided into different clades. Therefore, the presence or lack of a mixotrophic ability in this genus may be partially related to genetic characterizations. The results of this study suggest that Karenia species are not all mixotrophic, varying from the results of previous studies.

Food habits of the Red Fox Vulpes vulpes (Mammalia: Carnivora: Canidae) in Dachigam National Park of the Kashmir Himalaya, India

Food habits of the Red Fox Vulpes vulpes were studied in Dachigam National Park of the Kashmir Himalaya from December 2017 to November 2018 by scat analysis. A total of 246 scats were collected across seasons from different habitat types of the park. The diet of the Red Fox was characterized by a wider prey spectrum with small rodents, plants, and Himalayan Grey Langur Semnopithecus ajax as the major food items. The dietary behaviour showed slight seasonal variation with more invertebrates and plant material (fruits, berries, & grasses) during spring and summer. The food niche of the canid was wider in the warm season than in the cold season. Diet analysis revealed substantial use of anthropogenic food sources (human refuse and livestock carrion) by the Red Fox. The frequency of occurrence of human refuse and livestock carrion in the scats of the canid species varied seasonally. The results show that the Red Fox is an opportunistic feeder, and capable of adapting to a variety of dietary items.

Life-history omnivory in the fairy shrimp Branchinecta orientalis (Branchiopoda: Anostraca)

Very little is known about the feeding of naupliar and juvenile life stages of omnivorous fairy shrimps (Crustacea: Anostraca). Here, we aim to reveal whether the fairy shrimp Branchinecta orientalis is an ontogenetic omnivore and at which age and ontogenetic stage they gain the ability to feed on zooplankton. We assess how food uptake rates change with age until reaching maturity by providing algae (pico- and nanoplanktonic unicellular algae) and zooplankton (rotifers and copepod nauplii) as food in individual experiments. We found that the fairy shrimp B. orientalis started to feed on both types of algal prey immediately after hatching. Nanoplanktonic algae likely represented the most important food source until reaching maturity. Moreover, fairy shrimps started to feed on zooplankton already when they were 7 days old. Slow-moving rotifers gradually gained importance in the fairy shrimp diet with time. Our results reveal an ontogenetic change in the prey spectrum of fairy shrimp. The systematic shift towards omnivory likely affects both phyto- and zooplankton community composition, possibly contributing to temporal changes in food web dynamics in fairy shrimp habitats, and temporary ponds, which may warrant more detailed investigations in future studies.

Ecologically driven differences in individual diet specialization across three populations of Guiana dolphin.

Populations usually considered foraging generalists may include specialized individuals that feed on a restricted subset of the prey spectrum consumed by the population. By analyzing the time series of δ13C and δ15N values in sequential growth layer groups within tooth dentin, we measured population- and individual-level variation in resource use of three populations of Guiana dolphins (Sotalia guianensis)-Caravelas River, Babitonga Bay, and Norte Bay-along a latitudinal gradient in the southwestern Atlantic Ocean. We show that the Guiana dolphin at Caravelas River is a generalist population consisting of individual dietary specialists, likely due to the absence of other resident dolphin populations thus allowing individuals to target prey across a wide range of habitats. The Babitonga Bay population is also composed of individual specialists potentially due to the selective foraging behavior of some individuals on high-quality prey sources within and near the bay. In contrast, the Norte Bay population comprises individual generalists, which likely reflects its distinctive cohesive social organization, coexistence with two other dolphin species, and an opportunistic foraging strategy in response to resource fluctuations inherent to the southern limit of the species distribution. Although the Guiana dolphin is generally considered to be a dietary generalist at the population level, our findings reveal that the total niche width of populations and the degree of individual diet specialization are highly context dependent, suggesting dietary plasticity that may be related to a latitudinal gradient in resource availability and environmental conditions.

Parasitological survey of coastal birds from the Magellanic coast, Southwestern Atlantic Ocean

Ecto and endoparasites of four species of coastal birds, Haematopus ater, Larus dominicanus, Leucophaeus scoresbii (Charadriiformes), and Lophonetta specularioides (Anseriformes), are reported from Puerto Deseado on the Patagonian coast, Argentina. Only H. ater was infested with lice (Phthiraptera), belonging to 2 species (Ischnocera, Amblycera). A total of 19 helminth species were found parasitizing the coastal birds studied: 4 cestodes (1 Tetrabothriidae, 3 Cyclophyllidea); 11 trematodes (2 Gymnophallidae, 3 Microphallidae, 2 Notocotylidae, 1 Philophthalmidae, 2 Renicolidae, 1 Schistosomatidae); 3 nematodes (1 Anisakidae, 2 Acuariidae); and 1 acanthocephalan (Polymorphidae). Although some isolated records have been previously reported for these birds, the present work provides a parasitofauna study for H. ater, L. scoresbii, and L. specularioides for the first time. Endoparasites reflected the feeding habits of the birds; the parasite assemblage of L. dominicanus was the richest, indicating their wide prey spectrum and the diversity of the habitats frequented. A great species richness of trematodes, whose life cycles are partially known, suggests that L. specularioides feeds upon crustaceans and small bivalves. The blackish oystercatcher H. ater preys upon the limpet Nacella magellanica which hosts two larval trematodes corresponding to the adults found parasitizing it.

Сезонные аспекты питания Поволжской популяции солнечных орлов в гнездовой период

Сезонные аспекты питания Поволжской популяции солнечных орлов в гнездовой период

Patterns of livestock loss associated with a recolonizing wolf population in Germany

Predation on livestock presents a daunting challenge for human–carnivore coexistence in agricultural landscapes. In Germany, the recolonization of wolves is ongoing and its consequences are insufficiently understood. Knowledge about which livestock species are susceptible to wolf predation, which farm types are predisposed to attacks by wolves, and when predation on livestock occurs is valuable for mitigating stakeholder conflicts. To this end, we analyzed 14 years of monitoring data and assessed the livestock prey spectrum, identified correlates between predation on livestock, farm type and livestock category, and described temporal patterns of livestock loss caused by a recolonizing wolf population in the state of Brandenburg (Germany). Among a total of 1387 recorded cases, 42% were unequivocally attributed to wolves (SCALP criteria C1 and C2) and 12% of cases were not caused by wolves. The number of head of livestock killed during a single wolf attack was mediated by farm type and livestock species; losses per event were greater in full-time farms vs. other farm types and greater in sheep, farmed deer and other livestock species, compared to cattle. While sheep were the most commonly killed livestock species, the increase in wolf territories over the investigation period was associated with a widening of the domestic prey species spectrum. Count regression models provided evidence for the increasing frequency of predation events over the 14-year period, along with an exponential increase in wolf territories. Predation on livestock occurred throughout the year, yet seasonality of events was evident and differed across livestock categories. Predation on sheep peaked in the fall, coinciding with the post-weaning period of wolf offspring. Predation on cattle peaked in the spring, coinciding with the cattle calving period. These results call for renewed investment in the implementation of prevention methods for all susceptible domestic species, particularly during times of elevated predation risk.